Motor vehicle with tandem conversion attachment



Jan. 30, 1951 c. E. DORSEY, JR

MOTOR VEHICLE WITH TANDEM CONVEFSION ATTACHMENT 3 Sheets-Sheet 1 Nm QW Wm MW W Filed Feb. 18, 1949 c. E. DORSEY, JR 2,539,733

MOTOR VEHICLE WITH TANDEM CONVERSION ATTACHMENT Jan. 30, 1951 3 Sheets-Sheet 2 m 1 m b Alluring Filed Feb. 18, 1949 c. E. DORSEY, JR-

MOTOR VEHICLE WITH TANDEM CONVERSION ATTACHMENT Filed Feb. 18, 1949 Jan. 30, 1951 s Sheets-Sheet s ow I Patented Jan. 30, 1951 INT OKFEIEE.

MOTOR VEHICLE WITH TANDEM CON VERSION ATTAGHMEN '1 Claude E-.=-Dorse-y,; Jr Elba, Ala. Application"Februaryi18, 1949; Serial Noa- 77;1'46

8 Claims. (Cl. 280+-33.02.).

Thisinventi'on relates to a novelcon'struction of 'motor vehicle or truck" having'a dem'ountable tandem conversion unit for increasing theload capacity of the vehicle and by'rneans of'which the loadmay, be proportioned between'the motor vehicle and thetandem' conversion unit;

Another and primary" object of" the present invention is to provide atruck'tandem conversion assembly for"motor'trucks which is'so designed as to relievethe truck frameof" th'etor= sional or twisting strain to which'it is normally subjected when employed with a conventional tandem unit.

Another object of the'invention is to provide a conversion unit which'is soc'onstructed as to allow any. reasonable proportioning of the load between the truck axl'e'and'anaxle' of the conversion unit by longitudinally adjusting the con version'unit relatively to the truck frame.

Still another object of the invention" is to provide a conversion unit capable 'of'b'eing em ployed Without springs between its frame and axle and which is so connected to a truckframe as to utilize the springs thereof as its cushioning medium, through proper proportionin'g of the loadon the conversion unit and truck.

A further object of the invention is to provide a conversion unit which is capable of oscillatory movement relatively toa truck frame to which it is connectedin directions either longitud nally or transversely of the axis of the truck and conversion unit.

Still a further object of'the invention' is to provide a conversion unit having means to maintain' it incorrect alignment with theaxis-ofa motor vehicle; to which the unit'is connected," while moving around curves, to minimize the torsional strain transmitted to the truck or draft vehicle.

Various other objects and advantages of the invention will hereinafter" become more" fully apparent from the followingdescription of" the drawings; illustrating a. presently preferred: emr b'odiment thereof, and whereinrf Figure'l is a fragmentary top flan view show ing a motor vehicle equipped with the tandem conversion unit;

FigureZ is a rear elevational View thereof Figure 3 is a cross sectional view'taken sulfi stantially along a plane-as indicated-by the line 3-3: of Figure 1' and onan enlarged scale Figure i -is a fragmentary sideselevational .view oi the motorrvehicle' and conversioniunity Figure 5 is a cross sectional.viewthereoftaken' substantial y along a planaasv indicated: by the line 5-'-5" of Figure: 4 ,2 7

Figure 6 is a longitudinal substantially central sectional View taken-substantially along a. plane as indicated by -the :'1ine v(i -f Figure 1;,

Figure 7 'is. acrosswsectional View; on an en:- larged scale, taken substantiallyalong-a plane as indicated by the line l'l of Figure 4; and

- Figured is:a perspective-view o-f apartofthe:

structure.

Referring 1 more specificallyto the drawings; the motor-vehicle with tandem conversion unit attached is designa-ted generally I0 andcom-- prises the invention and includes a-motorwehicle; such as: a truck, designated: generally H; the frame" of which, rearwardlyrofz the-struck-- cab l2,- includes 1 longitudinally extending:- sill members It which are laterally spaced relatively to one another andwhich are? yieldably supported on the rear: axle H3 of the truck l I -by a conventional leaf -type truck-spring; l5.. A driven ground wheel is is fixed to each end oftherear axle l4 and saidlwhee-s it constitute thedriven wheels of stitut'i'ng the other part of .thestruck .andltandem combination it, includes a frame designated generally, 2!, composed-0f longitudinally extendi'ng, laterally spaced'sills 22 which are connected at their ends by cross braces23 and which may also be connected at .a plurality, of'longitudinally spaced'point's by additional cross braces, as required or desired. The frame 2| may be provided with upstandingcorner'posts 24 which rise from the corners formed by the sills 22' and braces 23; The sills 22, substantially intermediate of' their ends,- are provided with transversely aligned upwardly bowed portions 25 and r'earwardly thereof, eachof" said sills'has-a depending hanger Ztsecured'thereto; The hangers 2 6' are relatively 'widef in direction longitudina ly ofxthe frame': 2d, fora purpose? which :willihereine' after:becomexapparentzand are provided at" their lovverends; with bearing or; sleeve: port-ions 21 to receivean axlea 23; on1the ends of: which;ar.e.= jour.- naledground engaging wheels 29, constituting the supporting wheels. of: the tandem; unitvzlll,

A- -bearingtfl is secured topandlrises from each ofe the; cross: braces H- and said: bearings 30: are

disposed in longitudinal alignment with one another and in alignment with the longitudinal axis of the truck I I and tandem 28, as will hereinafter become apparent.

As a preferred method. of providing a flexible connection between the truck and tandem frames, a cross-shaped shaft, designated generally 3|, is provided with a longitudinally dis-- posed shaft portion 32 having spindles 33 projecting from the ends thereof and which are journaled in the bearings 35!. The other, transverse shaft 34 of the cross shaft 3|, which may be longer than the vided with similar spindles 35 which project from the ends thereof and which are journaled in bearings 36 which are fastened to and depend from the sills 22 and which are arranged in transverse alignment. The bearings 38 are disposed forwardly of the upwardly bowed sill portions 25, which portions are preferably disposed approximately over the truck axle Hi; however, the bearings 35 may be displaced forwardly or rearwardly relatively to the sills 22 for varying the proportioning of the load between the truck II and tandem trailer 20, as will hereinafter become apparent. It will be noted, and as clearly illustrated in Figures 4 and 5, that the bearings 30 will support the sills 22 substantially above the level of the sills l3 to allow the cross shaft 3| to rock on its longitudinal axis as provided by its shaft 32 and as seen in Figures 2, 3 and 5,

the sills 22 are spaced a sufficiently greater disw tance apart than the sills E3 to permit said sills 22 to straddle the sills |3. When the bearings 35 are mounted in a normal position, as illustrated in Figure 4, the rear end portions of the sills l3 will extend rearwardly to between the relatively wide web portions of the hangers 26 and said hangers are spaced so as to straddle said rear end portions of the sills l3 and are disposed in sufliciently close proximity thereto to maintain the truck frame and tandem frame in alignment when the combination vehicle Ill is moving around a curve thereby relieving both the truck and tandem frames of twisting and torsional strains which would otherwise be exerted thereon.

The shaft portions 32 and 3d of the cross shaft 3| are preferably provided with reinforcing or strengthening webs or flanges 31.

As best illustrated in Figure 3, a shaft 33 extends transversely of the frame 2|, adjacent its forward end, and is iournaled in bearings 39 and 50 which are connected to the sills 22. One end of the shaft 38 protrudes outwardly from one of the sills 22 and has a crank 4| fixed thereto for revolving the shaft 33. A ratchet wheel 42 is also fixed to said end of the shaft 38, as best seen in Figure 4 and is adapted to be engaged by a gravity actuated pawl 43 to normally hold said shaft against rotation in one direction. One or more cables 14 are wound on and secured to the shaft 38 and have depending free ends which are connected by eye bolt fastenings 25 to the cross brace IQ of the sills l3. By revolving the shaft 38 in one direction the cable or cables A l can be wound thereon for drawing the forward end of the tandem frame 2| downwardly to cause said frame to rock on its transverse pivots 35, 35 to elevate the rear end of the tandem frame to raise the wheels 29 thereof out of contact with a surface 26 so that the vehicle m can travel without a load and with the conversion unit 2i? supported entirely by the truck The pawl 43 will hold the shaft 38 to prevent it from turnlongitudinal shaft 32, is proing in a direction to permit the unwinding of the cables 44, until said pawl is manually released.

When the pawl 43 is released and swung away from the ratchet wheel 42 so that the cables 44 can unwind from the shaft 38, the rear end portion of the tandem frame 2| will swing downwardly and will be supported by the ground wheels 29. The tandem frame 2| can be loaded and the load so arranged thereon that it will be borne in desired proportions by the tandem axle 28 and the rear truck axle I i, preferably with forty to fifty percent of the load borne by the truck axle and the remainder of the load borne by the tandem axle 28. As previously stated, by moving the bearings 36 forwardly or rearwardly the proportioning of the load between the truck and tandem can be varied as desired. It will be readily apparent that the conversion frame 2| is capable of rocking substantially universally relatively to the truck frame, that is, on an axis either longitudinally or transversely of the truck frame so that in moving over uneven ground the tandem frame and truck frame may rock independently of one another in directions longitudinally or laterally without exerting a torsional strain or stress one upon the other, thereby eliminating all of the strain or stresses incident to a rigidly mounted tandem frame and the complicated systems of equalizers which are accordingly required.

Whereas in the embodiment of the invention as disclosed, the entire weight of the load is cushioned by the truck springs l5, it will be readily apparent that to accommodate particularly heavy loads similar leaf springs could be substituted for the hangers 26 to yieldably mount the tandem frame 2| on the axle 28.

Various modifications and changes are contemplated and may obviously be resorted to, without departing from the spirit or scope of the invention as hereinafter defined by the appended claims.

I claim as my invention:

1. A wheeled vehicle comprising a motor truck, said truck having a frame extending rearwardly from a cab thereof and yieldably supported by rear wheels of the truck; a tandem conversion unit including an elongated frame having a forward portion normally disposed over the rearwardly extending frame of the truck and including longitudinally extending laterally spaced sills, said sills being spaced a greater distance apart than the width of the truck frame for straddling the truck frame, laterally spaced wheels for supporting the conversion unit and disposed rearwardly of said rear truck wheels, and a flexible connection for connecting the truck frame to the tandem frame for rocking movement of the frames relatively toone another on axes disposed longitudinally and transversely of the wheeled vehicle, said flexible connection including a cross-shaped shaft, longitudinally aligned bearings fixedly secured to the truck frame forjournaling aligned ends of the crossshaped shaft, and transversely aligned bearings fixedly fastened to the conversion unit frame for journaling the other aligned ends of the crossshaped shaft.

2. A wheeled vehicle comprising a motor truck, said truck having a frame extending rearwardly from the cab thereof and yieldably supported by rear wheels of the truck; a tandem coinversion unit including an elongated frame having a forward portion normally disposed over the rearwardly extending frame of the truck and includshaped shaft, longitudinally aligned bearings fixedly secured to the truck frame for journaling aligned ends of the cross-shaped shaft, and transversely aligned bearings fixedly fastened to the conversion unit frame forjournaling the other aligned ends of the cross-shaped shaft, said first mentioned bearings being disposed in alignment with the longitudinal axis of the wheeled vehicle.

3. A wheeled vehicle comprising a motor truck, said truck having a frame extending rearwardly from the cab thereof and yieldably supported by rear wheels of the truck; a tandem conversion unit including an elongated frame having a forward portion normally disposed over the rearwardly extending frame of the truck and including longitudinally extending laterally spaced sills, said sills being spaced a greater distance apart than the width of the truck frame for straddling the truck frame, laterally spaced wheels for supporting the conversion unit and disposed rearwardly of said rear truck Wheels, and a flexible connection for connecting the truck frame to the tandem frame for rocking movement of the frames relatively to one another on axes disposed longitudinally and transversely of the wheeled vehicle, and means adjustably connecting the forward end of the tandem conversion unit frame to the truck frame for rocking the tandem conversion unit on the flexible connection to support said unit on the truck frame with the wheels thereof in an elevated position.

4. A wheeled vehicle comprising a motor truck, said truck having a frame extending rearwardly from the cab thereof and yieldably supported by rear wheels of the trucks; a tandem conversion unit including an elongated frame having a forward portion normally disposed over the rearwardly extending frame of the truck and including longitudinally extending laterally spaced sills, said sills being spaced a greater distance apart than the width of the truck frame for straddling the truck frame, laterally spaced wheels for supporting the conversion unit and disposed rearwardly of said rear truck wheels, and a flexible connection for connecting the truck frame to the tandem frame for rocking movement of the frames relatively to one another on axes disposed longitudinally and transversely of the wheeled vehicle, an axle on which the wheels of the tandem conversion unit are mounted, hanger brackets connecting the conversion unit frame to said axle and disposed to straddle the rear end of the truck frame.

5. A tandem conversion unit for wheeled vehicles comprising, in combination with a long wheel base motor vehicle having a frame extending rearwardiy from the vehicle cab and yieldably supported by rear wheels of the motor vehicle, an elongated tandem unit conversion frame having a forward end disposed over the truck frame forwardly of the rear wheels thereof and a rear portion extending rearwardly of the rear end of the truck frame, said rear truck wheels being disposed approximately intermediate of the ends of the conversion frame, a pair of laterally spaced wheels supporting the rear end of the tandem frame and disposed rearwardly of the rear truck wheels, and a flexible connection between the truck frame and tandem frame for rocking movement of s id frames relatively to one another on axes disposed longitudinally and transversely of the frames, said flexible connection being disposed approximately intermediate of the forward end of the conversion frame and the rear truck wheels.

6. A tandem conversion unit as in claim 5, said flexible connection including a pair of shafts connected in crossed relationship, a pair of bearings fixed to the truck frame and disposed in alignment with the axis thereof for journaling the ends of one of said shafts, and a pair of transversely aligned bearings fixed to the conversion unit frame for journaling the ends of the other of said shafts.

7. A tandem conversion unit as in claim 5, and means for drawing the forward end of the conversion unit frame downwardly with respect to the truck frame for elevating the wheels of the conversion unit.

3. A tandem conversion unit as in claim 5, said flexible connection including a pair of shafts connected in crossed relationship, a pair of bearings fixed to the truck frame and disposed in alignment for journaling the ends of one of said shafts, and a pair of aligned bearings fixed to the conversion unit frame for journaling the ends of the other of said shafts, one of said shafts being disposed in axial alignment with the truck frame and conversion unit frame and the other shaft being disposed transversely thereof.

CLAUDE E. DORSEY, J 2.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 927,256 Luthke July 6, 1909 1,179,793 Barber Apr. 18, 1916 1,377,138 Morrison May 3, 1921 2,360,654 Day Oct. 17, 1944 

